In recent years, in the production of semiconductor elements and liquid crystal display elements, fine patterning has been developed rapidly with advances in lithography techniques. Accordingly, there is a demand for high resolution such as a pattern having a width of 50 nm or less.
In general, as a fine patterning technique, shortening the wavelength of a light from an exposing source is employed, and there have been proposed a lithography technique using an exposure light such as ArF, F2, EUV, X-ray, electron beam and other charged particle beam besides currently available KrF excimer laser light. In lithography techniques using these exposure lights, a more sensitive, chemically amplified photosensitive composition has been used.
For example, a negative-working, chemically amplified photosensitive composition contains an alkali-soluble resin, an acid generator component which generates acid when exposed to light, a cross-linking agent, a basic compound, etc. Such a photosensitive composition is changed from an alkali-soluble composition to an alkali-insoluble composition when the resin is cross-linked to the cross-linking agent by the action of an acid that is generated from the acid generator component by exposure to light. Furthermore, the acid generated by the cross-linking reaction reacts catalytically and repeatedly, thereby realizing pattern exposure with a smaller amount of exposure light.
Processing accuracy is important as well as processing size. For example, it has been pointed out that a large variation in pattern sizes, which is shown by the line edge roughness (LER) value, affects the performance of a semiconductor and results in a serious problem.
In semiconductor lithography, conventionally, a resist material based on a polymer having a mass average molecular weight of about 10,000 or more has been used.
However, such a polymer material has a high molecular weight and broad molecular weight distribution, and thus has limited processing size and accuracy in fine patterning.
Accordingly, a low molecular material having a low molecular weight and small molecular size has been developed. Compared to the polymer material, such a low molecular material is expected to have excellent resolution and be less likely to contribute to an increase in LER. As such a low molecular material, there may be mentioned a calix resorcinarene derivative, and negative- and positive-working resist compositions prepared by using the calix resorcinarene derivative have been studied (see Patent Literatures 1 and 2).
Patent Literature 1 discloses a chemically amplified, negative-working radiation-sensitive composition which contains a calix resorcinarene compound (cyclic polyphenol compound) obtained by polycondensation of a resorcinol with an acetaldehyde in the presence of acid catalyst.
The calix resorcinarene compound is, however, highly crystalline and has low solubility in organic solvents that are used for film formation. Although the composition is a chemically amplified composition that is normally considered to have high sensitivity, the use of the calix resorcinarene compound is problematic in that the sensitivity of the composition is remarkably decreased and no sufficient resolution and LER value are provided to the resulting fine pattern.
Also in Patent Literature 1, a 0.1% tetramethylammonium hydroxide (TMAH) aqueous solution is used as the developer. When such a dilute TMAH aqueous solution is used as the developer, it is neutralized by carbon dioxide in the air. As a result, the sensitivity is varied, and it becomes difficult to stably obtain a product.
Patent Literature 2 discloses a calix resorcinarene derivative in which eight phenolic hydroxyl groups are each substituted with a protective or cross-linkable group. The resist composition containing the calix resorcinarene derivative can be used as a negative-working resist composition; however, it has lower sensitivity than chemically amplified resist composition since its cross-linking reaction is promoted by non-chemically amplified reaction mechanism. Also, since all of the phenolic hydroxyl groups of the calix resorcinarene derivative are each protected by a protective or cross-linkable group, the calix resorcinarene derivative slightly dissolves in alkaline developer, and an organic solvent is thus used as the developer. Because of these reasons, it is not clear whether or not it is possible to achieve desired performance when such a non-chemically amplified resist material is used in place of a chemically amplified resist material for which an alkaline developer is used in developing process.    Patent Literature 1: Japanese Patent Application Laid-Open (JP-A) No. H10-239843    Patent Literature 2: JP-A No. 2004-18421